xref: /third_party/ffmpeg/libavcodec/pthread.c (revision cabdff1a) 
1/*
2 * Copyright (c) 2004 Roman Shaposhnik
3 * Copyright (c) 2008 Alexander Strange (astrange@ithinksw.com)
4 *
5 * Many thanks to Steven M. Schultz for providing clever ideas and
6 * to Michael Niedermayer <michaelni@gmx.at> for writing initial
7 * implementation.
8 *
9 * This file is part of FFmpeg.
10 *
11 * FFmpeg is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; either
14 * version 2.1 of the License, or (at your option) any later version.
15 *
16 * FFmpeg is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
19 * Lesser General Public License for more details.
20 *
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with FFmpeg; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 */
25
26/**
27 * @file
28 * Multithreading support functions
29 * @see doc/multithreading.txt
30 */
31
32#include "libavutil/thread.h"
33
34#include "avcodec.h"
35#include "codec_internal.h"
36#include "pthread_internal.h"
37#include "thread.h"
38
39/**
40 * Set the threading algorithms used.
41 *
42 * Threading requires more than one thread.
43 * Frame threading requires entire frames to be passed to the codec,
44 * and introduces extra decoding delay, so is incompatible with low_delay.
45 *
46 * @param avctx The context.
47 */
48static void validate_thread_parameters(AVCodecContext *avctx)
49{
50    int frame_threading_supported = (avctx->codec->capabilities & AV_CODEC_CAP_FRAME_THREADS)
51#if FF_API_FLAG_TRUNCATED
52                                && !(avctx->flags  & AV_CODEC_FLAG_TRUNCATED)
53#endif
54                                && !(avctx->flags  & AV_CODEC_FLAG_LOW_DELAY)
55                                && !(avctx->flags2 & AV_CODEC_FLAG2_CHUNKS);
56    if (avctx->thread_count == 1) {
57        avctx->active_thread_type = 0;
58    } else if (frame_threading_supported && (avctx->thread_type & FF_THREAD_FRAME)) {
59        avctx->active_thread_type = FF_THREAD_FRAME;
60    } else if (avctx->codec->capabilities & AV_CODEC_CAP_SLICE_THREADS &&
61               avctx->thread_type & FF_THREAD_SLICE) {
62        avctx->active_thread_type = FF_THREAD_SLICE;
63    } else if (!(ffcodec(avctx->codec)->caps_internal & FF_CODEC_CAP_AUTO_THREADS)) {
64        avctx->thread_count       = 1;
65        avctx->active_thread_type = 0;
66    }
67
68    if (avctx->thread_count > MAX_AUTO_THREADS)
69        av_log(avctx, AV_LOG_WARNING,
70               "Application has requested %d threads. Using a thread count greater than %d is not recommended.\n",
71               avctx->thread_count, MAX_AUTO_THREADS);
72}
73
74int ff_thread_init(AVCodecContext *avctx)
75{
76    validate_thread_parameters(avctx);
77
78    if (avctx->active_thread_type&FF_THREAD_SLICE)
79        return ff_slice_thread_init(avctx);
80    else if (avctx->active_thread_type&FF_THREAD_FRAME)
81        return ff_frame_thread_init(avctx);
82
83    return 0;
84}
85
86void ff_thread_free(AVCodecContext *avctx)
87{
88    if (avctx->active_thread_type&FF_THREAD_FRAME)
89        ff_frame_thread_free(avctx, avctx->thread_count);
90    else
91        ff_slice_thread_free(avctx);
92}
93
94av_cold void ff_pthread_free(void *obj, const unsigned offsets[])
95{
96    unsigned cnt = *(unsigned*)((char*)obj + offsets[0]);
97    const unsigned *cur_offset = offsets;
98
99    *(unsigned*)((char*)obj + offsets[0]) = 0;
100
101    for (; *(++cur_offset) != THREAD_SENTINEL && cnt; cnt--)
102        pthread_mutex_destroy((pthread_mutex_t*)((char*)obj + *cur_offset));
103    for (; *(++cur_offset) != THREAD_SENTINEL && cnt; cnt--)
104        pthread_cond_destroy ((pthread_cond_t *)((char*)obj + *cur_offset));
105}
106
107av_cold int ff_pthread_init(void *obj, const unsigned offsets[])
108{
109    const unsigned *cur_offset = offsets;
110    unsigned cnt = 0;
111    int err;
112
113#define PTHREAD_INIT_LOOP(type)                                               \
114    for (; *(++cur_offset) != THREAD_SENTINEL; cnt++) {                       \
115        pthread_ ## type ## _t *dst = (void*)((char*)obj + *cur_offset);      \
116        err = pthread_ ## type ## _init(dst, NULL);                           \
117        if (err) {                                                            \
118            err = AVERROR(err);                                               \
119            goto fail;                                                        \
120        }                                                                     \
121    }
122    PTHREAD_INIT_LOOP(mutex)
123    PTHREAD_INIT_LOOP(cond)
124
125fail:
126    *(unsigned*)((char*)obj + offsets[0]) = cnt;
127    return err;
128}
129